Corrosion resistant copper alloys



United States Patent 3,416,915 CORROSION RESISTANT COPPER ALLOYS Tsuneaki Mikawa, 561l, l-Chome, Nakadai-cho,

Itabashi-ku, Tokyo, Japan N0 Drawing. Filed June 8, 1966, Ser. No. 559,957

Claims priority, application Japan, June 23, 1965,

3 Claims. (Cl. 75-159) This invention relates to copper base alloys and more particularly to a series of new corrosion resistant copper alloys having highly desirable properties. The invention further concerns a process for producing the copper alloys of the invention.

Copper is an extremely important material and is superior to most other metals in the combination of its excellent properties such as high electrical and thermal conductivity, high corrosion resistance, and high plastic workability. The high electrical conductivity of copper is particularly an important property.

While copper has relatively good corrosion resistance and undergoes almost no change in moist air, it produces so called verdigris of green color in the presence of carbon dioxide gas, and also is severely corroded by aqueous solutions of salts and by ammonium salts.

The objects of the present invention are to increase the oxidation and corrosion resistance of copper alloys, to cause copper alloys to assume a golden color and have rust resistance thereby to exhibit continuously their unique luster, to lower their melting points and to facilitate their working processes thereby to improve their properties desirable for various crafts and industries using copper base alloys.

In the achievement of these objects, in general, effective results have been obtained by adding: aluminum for the desired colorations; boron, nickel and several other metals for rust resistance; and iron for good workability.

More specifically and concisely stated, the present invention provides a series of corrosion resistant copper alloys containing from 0.1 to 10 percent of aluminum, from 0.1 to 10 percent of nickel, from 0.001 to 5 percent of boron, from 0.01 to 3 percent of titanium, from 0.001 to 1 percent of carbon, and the remainder of copper, all percentages being by weight.

The above set forth constituents and their proportions according to the invention have been selected for the following reasons:

1. ALUMINUM, 0.1-l0 PERCENT Aluminum has a low specific gravity, good corrosion resistance and plastic workability, and high electrical and thermal conductivity, as well as aesthetically pleasant appearance. The invention contemplates utilization of these properties to increase the corrosion resistance and promote the age hardening of the objective copper alloys and to impart to these alloys mechanical strength comparable to that of mild steel and golden color. It was found that a proportion of aluminum exceeding percent gives rise to difficulty in working the alloys, while a proportion of less than 0.1 percent lowers their corrosion resistance.

2. NICKEL, 0.1-1O PERCENT Nickel improves the corrosion resistance, mechanical properties, heat resistance, and strength of alloys. It was found that when nickel is added in a quantity exceeding 10 percent, working of the alloy becomes difficult, while addition thereof in a quantity less than 0.1 percent produces no results with respect to all desirable characteristics.

3. BORON, 0.001-5 PERCENT Boron is added for purposes such as increasing the Patented Dec. 17, 1968 ICE hardness of the alloys, neutralizing the detrimental effects of impurities, increasing the heat resistance and corrosion resistance of the alloys, and deoxidizing the copper. It was found that an addition of boron exceeding 1 percent impairs the workability of the alloys, while an addition of boron of less than 0.001 percent produces no favorable effect.

4. IRON, 0.0l-5 PERCENT Iron imparts good workability, high corrosion resistance, and heat resistance to the alloys. It was found that an addition of iron exceeding 5 percent raises the melting point and impairs the workability of the alloys, while that less than 0.01 percent produces no favorable elfect.

5. SILICON, 0.015 PERCENT Silicon is added for purposes such as improving the corrosion resistance weldability, mechanical properties, and age hardening of the alloys and deoxidization. It was found that an addition of silicon exceeding 5 percent impairs the workability of the alloys, while that less than 0.01 percent produces no favorable effect.

6. TITANIUM, 0.01-3 PERCENT Titanium is added for purposes such as improving the corrosion resistance, heat resistance, and workability of the alloys and deoxidization. It was found that an addition of titanium exceeding 3 percent impairs the workability of the alloys, while that less than 0.01 has no favorable effect.

7. CARBON, 0.001-l PERCENT Carbon is added for purposes such as improving the strength and other mechanical properties of the alloys. It was found that an addition of carbon exceeding 1 percent impairs the workability, while that less than 0.001 percent has no favorable effect.

8. COPPER REMAINDER Copper functions to produce various colors of the alloys.

In order to indicate still more fully the nature and utility of the present invention the following example of alloy composition and its alloying procedure as well as results of comparative tests are set forth, it being understood that the example is presented as illustrative only, and that it is not intended to limit the scope of the invention.

Example Alloy composition by weight: aluminum 6 percent; nickel 3 percent; boron 0.04 percent; titanium 0.5 percent; iron 3 percent; carbon 0.06 percent; silicon 0.5 percent; and copper remainder.

This alloy is alloyed by: first melting the copper and nickel; adding thereto an intermediate alloy of the iron, carbon, titanium, and boron, or an intermediate alloy of boron, copper and aluminum, iron, carbon, and titanium; further adding silicon; finally adding aluminum; and deoxidizing the alloy, the melting process being carried out at a temperature of from 1,150 to 1,250 degrees C.

The alloy produced in this mannner exhibits a golden metallic luster has resitsance against sulfidization, rust resistance, and a melting point of approximately 1,100 degrees C., and is readily melted and readily worked mechanically. Examples of products made of this alloy have been found satisfactory as decorative and industrial design products, utility goods, untensils, architectural materials, automotive parts, and machine parts.

Samples of a corrosion resistant copper alloy according to the invention and similar samples of another alloy (trade name atomic Gold) were subjected to comparative chemical tests consisting of immersion tests for 72 hours at 'a temperature of 37 degree C. respectively in aqueous solutions of hydrochloric acid, table salt, sodium sulfide, and lactic acid, four different concentrations of each solution being used.

The results of these tests are shown in the following Table 1.

alloy, said process being carried out at a temperature of from 1,150 to 1,250 degrees C., thereby to produce an alloy having the essential composiiton by weight of from 0.1 to 10 percent of aluminum, from 0.1 to 10 percent of nickel, from 0.001 to 5 percent of boron, from 0.01 to 5 percent of iron, from 0.01 to 5 percent of silicon, from 0.01 to 3 percent of titanium, from 0.001 to 1 percent of carbon, and the remainder of copper.

TABLE l.-RESULTS OF COMPARATIVE IMMERSION TESTS ABOUT THE CORROSION RESISTANT COPPER ALLOYS OF THIS INVENTION AND SO CALLED ATOMIC GOLD [This invented alloy] Concentration, percent Chemical 0.5 1 2 5 Hydrochloric acid No weight loss; no No weight loss; slight No weight loss; slight No weight loss; slight discoloring. discoloring. discoloring. discoloring. Table salt do No weight loss; no No weight loss; no No weight loss; no

discoloring. discoloring. discoloring. Sodium sulfide do do do Do. Lactic acid do do do Do.

[Alloy Atomic Gold] Hydrochloric acid No weight loss; slight Weight loss 0.081 mg.; Weight loss 0.012 mg.; Weight loss 0.10 mg;

discoloring. discolored. discolored. discolored. Table salt do Slight weight loss; Weight loss 0.004 n1g.; Weight loss 0.06 mg;

discolored. discolored. discolored. Sodlum sulfide "do do Slight weight loss; Slight weight loss; discolored. discolored. Lactic acid ...do do do Do.

Samples of the corrosion resistant copper alloy according to the invention and similar samples of other alloys (trade names Cactus Gold and Atomic Gold) were subjected to comparative physical tests, the results of which are shown in Table 2.

TABLE 2.-RESULTS OF COMPARATIVE PHYSICAL TESTS What I claim is:

1. A corrosion resistant copper alloy having the essential composition by weight of: from 0.1 to percent of aluminum; from 0.1 to 10 percent of nickel; from 0.001 to 5 percent of boron; from 0.01 to 5 percent of iron; from 0.01 to 5 percent of silicon; from 0.01 to 3 percent of titanium; from 0.001 to 1 percent of carbon; and the remainder of copper.

2. A process for producing corrosion resistant copper alloys which comprises: melting together copper and nickel; adding thereto an intermediate alloy of iron, carbon, titanium, and boron; further adding silicon; still further adding aluminum; and deoxidizing the resultant 3. A process for producing corrosion resistant copper alloys which comprises: melting together copper and nickel; adding thereto an intermediate alloy of boron, copper, and aluminum, iron, carbon, and titanium; further adding silicon; still further adding aluminum; and deoxidizing the resutling alloy, said process being carried out at a temperature of from 1,150 to 1,250 degrees C., thereby to produce an alloy having the essential composition by weight of from 0.1 to 10 percent of aluminum, from 0.1 to 10 percent of nickel, from 0.001 to 5 percent of boron, from 0.01 to 5 percent of iron, from 0.01 to 5 percent of silicon, from 0.01 to 3 percent of titanium, from 0.001 to 1 percent of carbon, and the remainder of copper.

References Cited UNITED STATES PATENTS 1,778,668 10/1930 Fuller -159 2,031,315 2/1936 Jennison 75-159 2,482,225 9/1949 Sykes 75159 2,783,143 2/1957 Johnson et a1. 75-159 3,258,334 6/1966 Kessler 75159 3,364,016 1/1968 Mikawa 75l59 CHARLES N. LOVELL, Primary Examiner.

US. 01. X.R. 

1. A CORROSION RESISTANT COPPER ALLOY HAVING THE ESSENTIAL COMPOSITION BY WEIGHT OF: FROM 0.1 TO 10 PERCENT OF ALUMINUM; FROM 0.1 TO 10 PERCENT OF NLICKEL; FROM 0.001 TO 5 PERCENT OF BORON; FROM 0.01 TO 5 PERCENT JOF IRON; FROM 0.01 TO 5 PERCENT OF SILICON; FRO 0.01 TO 3 PERCENT OF TITANIUM; FROM 0.001 TO 1 LPERCEDNT OF CARBON; AND THE REMAINDER OF COPPER. 